This game was the antithesis of their 5-0 win in the first leg at the Estadio do Dragao, but a professional performance, a fifth clean sheet in eight European matches and no apparent injuries represented mission accomplished.
While supporters may have had a justifiable complaint for being short-changed by the Champions League's top scorers, from Jurgen Klopp's point of view there was no point in taking any risks -- especially with Saturday lunchtime's match at Manchester United looming large.
Manager Klopp made five changes -- two more than he had suggested prematch -- with the most significant being a rest for 32-goal forward Mohamed Salah and a first start in two months for Adam Lallana.
Whether alterations, the five-goal cushion from the first leg or the imminent visit to Old Trafford affected the occasion is open to debate, but the game was played at a much lower intensity that what is considered the norm.
It was reflected in the first-half statistics which showed Liverpool failed to have a single shot on target in the opening 45 minutes for only the second time this season and the first time since the 1-1 draw at home to Chelsea in November.
Sadio Mane, having volleyed over a good chance from Joe Gomez's cross, came closest on the half-hour when he chested down James Milner's diagonal ball and shot past Iker Casillas, making his 167th Champions League appearance, but saw the ball rebound off the post.
Lovren flicked a header onto the roof of the net from a free-kick by Milner, who with better finishing from his team-mates would have added to his competition-leading seven assists.
The former England midfielder took matters into his own hands early in the second half but sliced horribly wide from Lallana's cross.
Porto's response was to force the first save of the night from either goalkeeper with Loris Karius tipping wide Majeed Waris' strike from distance, while Roberto Firmino's run through on goal was halted by the visitors' captain Felipe.
Firmino, no doubt with Saturday's match against Jose Mourinho's side in mind, was spared the final 30 minutes as Danny Ings made his first Champions League appearance at Anfield and, with time ticking away, Salah was given a 20-minute run-out.
The in-form Egypt international had one angled shot easily saved as his run of scoring in successive matches ended at seven but, with a 24th European quarterfinal in the bag (14 in this competition), his talents will be required for a more important occasion.
Casillas, who emerged for the second half to a rousing ovation from the Kop, gave Anfield a reminder of his quality on potentially his final Champions League appearance by clawing away Ings' looping header late on.